RU2529026C1 - Method of producing saturated carboxylic acids - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of producing saturated carboxylic acids of general formula

includes hydrogenation of unsaturated carboxylic acids with hydrazine hydrate in the presence of a nickel catalyst while heating in aqueous sodium hydroxide solution for 3-4 hours. The unsaturated carboxylic acids to be hydrogenated are selected from: methacrylic acid, norbornene carboxylic acid and trans-cinnamic acid; the catalyst used is nickel nanoparticles obtained by reducing nickel (II) chloride hexahydrate with hydrazine hydrate in an aqueous alkaline medium in situ, and the process is carried out in molar ratio NaOH: unsaturated carboxylic acid of 1.3-1.5:1 at 60°C.

EFFECT: simple method of producing compounds of the disclosed structural formula.

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Description

The invention relates to a method for producing saturated carboxylic acids, in particular to a new method for the hydrogenation of unsaturated carboxylic acids, which is applicable in the laboratory and allows to obtain saturated carboxylic acids of the general formula

which are used as intermediates in organic synthesis.

A known enzymatic method for the hydrogenation of unsaturated fatty acids from a series of oleic, linoleic, linolenic using rumen bacteria [The Hydrogenation of Unsaturated Fatty Acids by Five Bacterial Isolates from the Sheep Rumen, Including a New Species / P. KEMP, R.W. WHITE, D.J. EANDER // Journal of General Microbiology (1975), 90, 100-114].

The disadvantages of the method are the need for growing microorganisms, low selectivity of hydrogenation.

A known method of hydrogenation of unsaturated carboxylic acids with hydrogen under a pressure of 3-150 atm and 100-400 ° C on a catalyst "Nickel on an oxide carrier" [Rekker; Tjalling; et al. Process For The Hydrogenation Of Fatty Acids Using A Promoted Supported Nickel Catalyst. US Patent Application 20130079535 A1]. The disadvantages of the method are the use of elevated temperatures and hydrogen under pressure.

A known method of hydrogenation of unsaturated carboxylic acids that are part of soybean oil with hydrogen at 1.5 MPa and 80 ° C in the presence of polymer stabilized ruthenium nanoparticles [Effect of Ru Nano-particle Size on Hydrogenation of Soybean Oil / Binbin Xu, Kong Yong Liew, Jin-lin Li // J Amer Oil Chem Soc (2007) 84: 117-122].

The disadvantages of the method are the high cost and inaccessibility of the catalyst, the use of hydrogen under pressure.

A known method of hydrogenation of unsaturated carboxylic acids, consisting in the reaction of unsaturated carboxylic acid dissolved in ethanol with the addition of 95% hydrazine and passing oxygen through the reaction mixture, which played the role of an oxidizing agent for hydrazine, forming diimide, which hydrogenated unsaturated acids. At the same time, a certain amount of heptadecanoic acid was introduced into the reaction mixture as a standard for identifying products by gas-liquid chromatography [Studies on the Mechanism of the Hydrazine Reduction Reaction: Applications to Selected Monoethylenic, Diethylenic and Triethylenic Fatty Acids of cis Configurations / W.M.N. Ratnayake, J.S. Grossert, R.G. Ackman // Journal of the American Oil Chemist's Society, 1990, Vol. 67, No. 12. - pp. 940-946].

The disadvantages of the method are the use of concentrated hydrazine, purging with oxygen the reaction mass. The reaction products were not isolated in pure form; they were determined by GLC in the form of their esters.

The closest analogue of the invention is a method of hydrogenation of unsaturated fatty acids with hydrazine hydrate in ethanol [Hydrogenation of Linolenate. II. Hydrazine Reduction / C.R. Schoifield, E.P. Jones, J. Nowakowska, E. Seike, H.J. Datton // Journal of the American Oil Chemist's Society, 1961. - Vol. 38, No. 4. - pp.208-211]. The hydrogenating agent was diimide, which was formed during the slow oxidation of hydrazine hydrate with atmospheric oxygen. Reaction products did not stand out individually; to determine the composition of the reaction mixture by GLC, the acid mixture was transferred to the corresponding esters.

The disadvantage of this method is the incomplete hydrogenation of unsaturated acids, individual products were not allocated. In this way, compounds of the claimed structural formula were not obtained.

The closest is a method of producing hydrocinnamic acid by hydrogenation of cinnamic acid in an aqueous alkaline medium with hydrazine hydrate when heated in the presence of Raney nickel [patent CN 102617328 A, publ. 08/01/2012].

The disadvantage of this method is the need for preliminary preparation of the catalyst, as well as the fact that this method was developed to obtain only one substance - hydrocinnamic acid.

The task is to develop a simple method for the hydrogenation of unsaturated acids of various structures.

The technical result is to increase the manufacturability of the method for producing saturated acids.

The set result is achieved in a method for producing saturated carboxylic acids of the general formula

consisting in the hydrogenation of unsaturated carboxylic acids with hydrazine hydrate in the presence of a nickel catalyst when heated in an aqueous solution of sodium hydroxide for 3-4 hours, characterized in that the unsaturated carboxylic acids from the series: methacrylic acid, norbornene carboxylic acid and trans-cinnamic acid are subjected to hydrogenation The catalyst used is nickel nanoparticles obtained by reduction of nickel (II) chloride hexahydrate with hydrazine hydrate in an aqueous alkaline medium in situ, and the process is carried out with a molar NaOH: unsaturated carboxylic acid ratio of 1.3-1.5: 1 at 60 ° C.

The essence of the method is the hydrogenation reaction of unsaturated carboxylic acids from the series: methacrylic acid, norbornene carboxylic acid and trans-cinnamic acid hydrazine hydrate in an aqueous medium with a slight excess of alkali in the presence of nickel nanoparticles.

The method is as follows.

The synthesis was carried out in one reaction volume with successive addition of reagents. First, an aqueous solution of sodium hydroxide is prepared so that this amount is sufficient to form an acid salt and obtain a catalyst. Then hydrogenated carboxylic acid is added, and at 60 ° C - hydrazine hydrate, the amount of which should also be sufficient both to obtain a catalyst and to restore unsaturated bonds. After this, an aqueous solution of nickel (II) nitrate or chloride is added and, at 60 ° C, a black colloidal catalyst solution is formed and the process of hydrogenation of the unsaturated acid salt begins. The reaction is completed after 3-4 hours, after which the product is isolated by acidification of the reaction mass with an aqueous solution of sulfuric acid. In this case, most of the particles of the nickel catalyst dissolve in an acidic solution, insoluble easily filtered off. After cooling the reaction mixture, the separated saturated acid is either filtered off or extracted from the aqueous solution and purified by distillation at atmospheric pressure or in vacuum. The yield of hydrogenation products is 65-75%.

It was found that the position of the multiple bond in the substrate molecule has little effect on the yield of the reaction products; it is shown that the trans isomerism of the substrate and the presence of substituents on the C = C bond do not interfere with the reaction.

The composition and structure of hydrogenation products are confirmed by ¹ H NMR spectroscopy, the properties of the known compounds are consistent with published data.

Thus, an easy preparative method was developed for hydrogenation of an unsaturated carbon-carbon bond in compounds containing a carboxyl group, flowing in water using available nickel salts and leading to the formation of saturated acids in high yield.

Stabilization of colloidal solutions of metal nanoparticles is not required, this greatly simplifies and cheapens the proposed method of hydrogenation. Since the same conditions are used in the synthesis of the catalyst and the reduction of the claimed compounds, the whole process is reduced to a single-stage synthesis, in which the catalyst is formed in situ from available nickel (II) chloride or nitrate.

The invention is illustrated by the following examples:

Example 1

2-carboxynorbornane.

8 g (0.2 mol) of sodium hydroxide, 50 ml of water are charged into a flat-bottomed flask equipped with a reflux condenser and 20 g (0.145 mol) of 5-carboxynorborn-2-ene are dissolved in the resulting mixture, after which 25 g (0.5 mol) of hydrazine hydrate are added and heated to 60 ° C, after which a solution of 4 g (0.017 mol) of nickel (II) chloride hexahydrate in 15 ml of water is added in portions. The resulting black solution was kept at 60 ° C and stirring for 4 hours, after which the reaction mixture was cooled, a solution of 24.5 g (0.25 mol) of sulfuric acid in 25 ml of water was added. After the nickel catalyst was dissolved and the product precipitated, it was extracted with diethyl ether, the solvent was distilled off from the organic layer, the residue was distilled, and 15.2 g (0.109 mol, 75%) of 2-carboxynorbornane were obtained, colorless. crist., mp 60 ° C, bp 147-149 ° C / 20 mmHg ¹ H NMR spectrum, δ, ppm: 1.09-1.80 m (8H, 4CH ₂ ); 2.21 m (1H, CH), 2.53 s (1H, CH); 2.71 m (1H, HCO), 12.20 s (1H, COOH).

Example 2

3-Phenylpropionic (hydrocinnamic) acid.

6 g (0.15 mol) of sodium hydroxide, 40 ml of water are loaded into a flat-bottomed flask equipped with a reflux condenser, and 14.8 g (0.1 mol) of trans-cinnamic acid are dissolved in the resulting mixture, after which 18 g (0.36 mol) of hydrazine hydrate are added and heated to 60 ° C, after which a solution of 3 g (0.013 mol) of nickel (II) chloride hexahydrate in 20 ml of water is added in portions. The resulting black solution was kept at 60 ° C and stirring for 4 hours, after which the reaction mixture was cooled, a solution of 24.5 g (0.25 mol) of sulfuric acid in 25 ml of water was added. After the nickel catalyst was dissolved and the product precipitated, it was extracted with diethyl ether, the solvent was distilled off from the organic layer, the residue was distilled, and 10 g (0.067 mol, 67%) of phenylpropionic acid were obtained, colorless. crist., mp 49 ° C, bp 279-281 ° C (lit. mp. 48.6 ° C, mp. 279.6 ° C [Alfa Aesar. Research Chemicals, Metals and Materials. 2006-2007]).

Example 3

Isobutyric acid.

(лит. т. кип. 154,4°C, $$n_D^{20}\mathrm{1,3930}$$

[Alfa Aesar. Research Chemicals, Metals and Materials. 2006-2007]).12 g (0.3 mol) of sodium hydroxide, 60 ml of water are charged into a flat-bottomed flask equipped with a reflux condenser and 20 g (0.233 mol) of methacrylic acid are dissolved in the resulting mixture, then 25 g (0.5 mol) of hydrazine hydrate are poured and heated to 60 ° C then a solution of 3 g (0.013 mol) of nickel (II) chloride hexahydrate in 30 ml of water is added in portions. The resulting black solution was kept at 60 ° C and stirring for 3 hours, after which the reaction mixture was cooled, a solution of 24.5 g (0.25 mol) of sulfuric acid in 25 ml of water was added. After the nickel catalyst was dissolved and the product precipitated, it was extracted with diethyl ether, the solvent was distilled off from the organic layer, the residue was distilled, and 14.2 g (0.161 mol, 70%) of isobutyric acid were obtained, colorless. liquid, t. 152-155 ° C, $$n_D^{\mathrm{twenty}}1.3933$$

(lit. t. boiling. 154.4 ° C, $$n_D^{\mathrm{twenty}}1.3930$$

[Alfa Aesar. Research Chemicals, Metals and Materials. 2006-2007]).

Thus, a method for producing saturated carboxylic acids has been developed, which proceeds with a high yield of starting materials, which consists in hydrogenating unsaturated carboxylic acids with hydrazine hydrate in an aqueous alkaline medium in the presence of nickel nanoparticles obtained from nickel (II) chloride in situ, and the process goes when heated for 3-4 hours at 60 ° C.

Claims (1)

The method of obtaining saturated carboxylic acids of the General formula

consisting in the hydrogenation of unsaturated carboxylic acids with hydrazine hydrate in the presence of a nickel catalyst when heated in an aqueous solution of sodium hydroxide for 3-4 hours, characterized in that the unsaturated carboxylic acids from the series: methacrylic acid, norbornene carboxylic acid and trans-cinnamic acid are subjected to hydrogenation The catalyst used is nickel nanoparticles obtained by reduction of nickel (II) chloride hexahydrate with hydrazine hydrate in an aqueous alkaline medium in situ , and the process is carried out with a molar NaOH: unsaturated carboxylic acid ratio of 1.3-1.5: 1 at 60 ° C.